1. Field of the Invention
Example embodiments of this invention relate to detecting sensor faults.
2. Related Art
An example of a situation where the detection of sensor faults is needed is in the case of a sensor of an internal combustion engine. As emissions requirements become more stringent, it becomes more important to ensure that sensors that are used in the control of an internal combustion engine are working correctly.
For example, it is likely that a requirement of the California Air resources Board (CARB) will be the detection of asymmetric malfunctions (i.e. that primarily affect only the lean-to-rich response rate or rich-to-lean response rate) and symmetric malfunctions (i.e., that affect both the lean-to-rich and rich-to-lean response rates) of an oxygen sensor in the exhaust system of an internal combustion engine.
As another example, the CARB may likely require that a diagnostic function detect an amount of time that a sensor, such as a vehicle's primary universal heated exhaust gas oxygen (UHEGO) sensor, takes to respond to a change in air-fuel ratio that causes the vehicle's tailpipe emissions to exceed legislated limits. That is, the CARB may require that the sensor's response time to an air-fuel ratio change that causes non-conforming tailpipe emission levels not exceed a certain threshold amount of time.
There is a need to provide a robust approach to the monitoring of a sensor response to facilitate the meeting of such requirements.